According to Wikipedia
Sakurai’s goal with Ultimate was to include every character from previous games despite the various development and licensing problems this would cause.
A few days ago, Nintendo Japan Officially printed a guide for smash Bros. ultimate. this book contains 832 pages.
If you look carefully at these images you will see Both Snake and Pokémon Trainer
It means amiibo for Pokémon Trainer and Solid Snake are on the way